Fully-integrated non-magnetic non-reciprocal components based on linear periodically-time-varying circuits

Lorentz reciprocity is a fundamental property of passive, linear, time-invariant circuits and systems constructed from conventional materials. Recently, we demonstrated the first CMOS non-magnetic non-reciprocal passive circulator that uses a linear periodically-time-variant (LPTV) phase-shifting N-path filter to break reciprocity. In this paper, we review the concept and present the measured performance of a 65nm CMOS 750MHz prototype that exhibits 1.7dB of loss in the transmitter-antenna (TX-ANT) and antenna-receiver (ANT-RX) paths and has high isolation (up to 50dB through tuning and 20dB bandwidth of 32MHz). Through an architectural feature specifically designed to enhance TX linearity, the circulator achieves an in-band (IB) TX-ANT IIP3 of +27.5dBm, remarkably two orders of magnitude higher than the ANT-RX IIP3 of +8.7dBm.